it is fancifil to think what they have now will cope let alone what will occur when they get RW3.
The converggence of 3 motorways means they will need to double the number of lanes within a 20 odd mile radius.just to keep up with current demand let alone Rw3.
And there you have hit the nail on the head. There is no way this road system will not be approved for major improvements at some point either before LHR expansion or in the following few decades.
This is why the argument against the third runway based on the cost to the taxpayer of the M4/M25 reconfiguration is such a red herring.
In actuality it is reasonable to suggest that doing both these projects in harmony would save costs significantly as well as only having 1 period of works and diversions etc in what must be one of the busiest intersections in the UK.